In a common contact for a flexible display, an electrical connection has to be made between a front plane laminate and an (active matrix) backplane. Problems arise during deflection of a top substrate during the lamination of the front plane. Controlling this deflection is desirable from the stand point of a common contact region in a display as will be explained. For displays that include two portions that need to be electrically connected, an anisotropic conducting sticker is currently employed to make the electrical connection between say a front plane conductive layer (e.g., the ITO) and a common contact on the back plane. This method suffers from several drawbacks.
In particular, there are three problems with the currently used solution for making the common contact:
1) The anisotropic sticker includes large irregular shaped metal particles which can damage the ITO layer during lamination. A common contact sticker includes irregular shaped metal particles over a common contact region. This may lead to unstable electrical contacts and the particles can damage adjacent layers.
2) The contact sticker should fit exactly or nearly exactly over the common contact site, as height differences and non-sticking areas may initiate buckling at the edges of the conducting tape. Height differences between the common contact, the sticker and surrounding areas are clearly observed in FIGS. 1A and 1B. In FIGS. 1A and 1B, two typical examples of the size mismatch between the common contact area (oval shape) and the common contact sticker (rectangular shape over the common contact area) can be seen. Also note the irregularly shaped metals particles visible in FIGS. 1A and 1B.
3) The current process to apply the stickers is a manual process and therefore expensive.